Hot mill-roll.



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1,1 30,91 1 Patented Mar. 9, 1915.

,UNITED STATES ,PATENT oEEIoE.

JACOB LooIvIIs, oE WHEELING, wEs'I` VIRGINIA.

HOT MILL-ROLL.

Specification of Letters Patent. l

Application led July 31, 1912, Serial No. 712,396. Renewed July 3, 1914.Serial No. 848,947.

T0 all whom it may concern.'

Be it known that I, JACOB LooMIs, a citizen of the United States,residing at Wheeling, in the county of Ohio and State of West Virginia.,have invented a new and useful Hot Mill-Roll, of which the following isa specification.

The object of my invention is to produce a roll which will have a longeraverage working life than those now commonly in use.

The accompanying drawings illustrate my improved roll in comparison withrolls of the type shown in my 1Batent No. 831,727, issued September 25,1906.

Figure 1 is an axial section of a casting from which my roll may bemachined; Fig. 2 is a section on line 2-2 of Fig. 1; Fig.l 8. a sideelevation of the core around which was cast the casting shown in Fig. 1;and Fig. 4 a transverse section of a hollow roll after surface crackshave developed.

In the operation of hollow rolls in rolling mills, for the production ofsheet metal, it is found that sooner or later very fine cracks willappear in the working faces. These fine cracksin many instances so fineas to be almost undiscernible by the unaided eyeproduce fineorcoarser-hair marks or ridges in the sheets and thus make the producteither uncommercial or low grade. These cracks in the rolls are, ingeneral, substantially parallel with the axis of the roll and are mostfrequently first found in the region of the plane indicated by thecorebox division mark left by the core around which the roll was cast.As is well known, these rolls are cast in molds having the axis of theroll (the core) vertical and the molten metal is introduced tangentiallynear the bottom of the mold. The main body of the mold contains a chillalong that portion of its length which is to be the sheet-rollingportion, and the molten metal therefore cools more slowly adjacent thecore. It is my opinion that, during this cooling, solidication (i. e.,contraction) stresses are set up in the metal immediately adjacent thecore which are tangential to the inner surface of the cast body and thatthose stresses result in minute cracks (or weaknesses tending to cracks)which extend lengthwise of the body substantially parallel with its axisand extend into the body in minute Vs which are substantially normal tothe interior of the roll, asV indicated at 10, 10 in Fig. 4, on anexaggerated scale. There will be many of these minute cracks insubstantially radial planes so that the roll may be analyzed as a barrelconsisting of a plurality of associated staves.

lPatented Mar. 9, 1915.

Vhen this roll is used it is, of course, subjected to enormous pres- Ysures inv axial planes and therefore in substantial coincidencesuccessively with the radial planes of the cracks 10. Ultimately theinitial cracks l0 areextended into cracks 11 which lead to the workingsurfacev 12. This further cracking of the roll is, in my opinion, theresult of the repeated coincidence of the crack-planes with the pressureplane and I have avoided the difliculty in the following manner. Insteadof providing a core having a surface of revolution, as is the practiceat present, I provide a core 13 having a surface composed of a pluralityof adjacent helical ribs 14. The main body of the core may be ofsubstantially uniform diameter but I prefer to continue the teachings ofmy Patent No. 831,727 and make the main body of the core of largerdiameter at its middle, thus making each rib 14 a helix of decreasingradius at both ends. v

When the roll V15 (Figs. 1 and 2) is cas around such a core there will,of course, be formed adjacent helical channels 16 within the roll and,as a result of the cooling stresses,the minute cracks 10', which areunavoidably formed,rwill be normal to the surfaces of the. channels and,insteadV of lying in radial planes relative to the axis of theroll,w'ill be in helices. As a consequence, these cracks can never bebrought into substantial coincidence withthe pressure plane but willalways lie diagonally with relation to that plane and the rollingpressure will not tend to further extend the initial cracks.

I claim as my invention:

. 1. A roll having an axialchamber whose i surface is formed by adjacenthelical channels of decreasing radii at both ends.

2. A roll having an axial chamber whose surface is formed by adjacenthelical chan- 'y hollow, and. the nterrvlal surface comprising ginie,this 20th day of July, A. D. one thouinvvardly projecting integral ribshaving a sand nine hundred and twelve.

general direction at an angle both to the axis of the rroll and a. planeat right angles JACOBLOOMIS [LS] thereto. 7Witnesses 'In witnesswhereof, I have hereuntoset WM. J. MURRAY,

my hand and seal at Wheeling, West Vir- Lome J. YAEGER.

Copies of this. patent may yhe obtained for five cents each, byaddressing Commissioner of Patents,

Washington, 2D. C.

